Hemicellulose in the context of "Wood"

Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of biofuels. It is composed of two kinds of carbohydrate polymers, cellulose and hemicellulose, and an aromatic-rich polymer called lignin. Any biomass rich in cellulose, hemicelluloses, and lignin are commonly referred to as lignocellulosic biomass. Each component has a distinct chemical behavior. Being a composite of three very different components makes the processing of lignocellulose challenging. The evolved resistance to degradation or even separation is referred to as recalcitrance. Overcoming this recalcitrance to produce useful, high value products requires a combination of heat, chemicals, enzymes, and microorganisms. These carbohydrate-containing polymers contain different sugar monomers (six and five carbon sugars) and they are covalently bound to lignin.

Lignocellulosic biomass can be broadly classified as virgin biomass, waste biomass, and energy crops. Virgin biomass includes plants. Waste biomass is produced as a low value byproduct of various industrial sectors such as agriculture (corn stover, sugarcane bagasse, straw etc.) and forestry (saw mill and paper mill discards). Energy crops are crops with a high yield of lignocellulosic biomass produced as a raw material for the production of second-generation biofuel; examples include switchgrass (Panicum virgatum) and elephant grass. The biofuels generated from these energy crops are sources of sustainable energy.

A corncob, also called corn cob or cob of corn, is the hard core of an ear of maize, bearing the kernels, made up of the chaff, woody ring, and pith. Corncobs contain mainly cellulose, hemicellulose, and lignin.

The cob is not toxic to humans and can be digested, but the outside is rough and practically inedible in its original form. The foamy pith has a peculiar texture when mature and is completely bland, which most people would find unappealing, due to the consistency similar to foam plastic.

Polysaccharides (/ˌpɒliˈsækəraɪd/; from Ancient Greek πολύς (polús) 'many, much' and σάκχαρ (sákkhar) 'sugar') are "Compounds consisting of a large number of monosaccharides linked glycosidically". They are the most abundant carbohydrates in food. Their structures range from linear to highly branched polymers. Examples include storage polysaccharides such as starch, glycogen, and galactogen and structural polysaccharides such as hemicellulose and chitin. The term "glycan" is synonymous with polysaccharide, but often glycans are discussed in the context of glycoconjugates, i.e. hybrids of polysaccharides and proteins or lipids.

Polysaccharides are often heterogeneous, containing slight modifications of the repeating unit. They may be amorphous (e.g. starch) or insoluble in water (e.g. cellulose).

Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamentous forms. Xanthophyte chloroplasts contain the photosynthetic pigments chlorophyll a, chlorophyll c, β-carotene, and the carotenoid diadinoxanthin. Unlike other Stramenopiles (heterokonts), their chloroplasts do not contain fucoxanthin, which accounts for their lighter colour. Their storage polysaccharide is chrysolaminarin. Xanthophyte cell walls are produced of cellulose and hemicellulose. They appear to be the closest relatives of the brown algae.

A cell wall is a structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. Another vital role of the cell wall is to help the cell withstand osmotic pressure and mechanical stress. While absent in many eukaryotes, including animals, cell walls are prevalent in other organisms such as fungi, algae and plants, and are commonly found in most prokaryotes, with the exception of mollicute bacteria.

The composition of cell walls varies across taxonomic groups, species, cell type, and the cell cycle. In land plants, the primary cell wall comprises polysaccharides like cellulose, hemicelluloses, and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae exhibit cell walls composed of glycoproteins and polysaccharides, such as carrageenan and agar, distinct from those in land plants. Bacterial cell walls contain peptidoglycan, while archaeal cell walls vary in composition, potentially consisting of glycoprotein S-layers, pseudopeptidoglycan, or polysaccharides. Fungi possess cell walls constructed from the polymer chitin, specifically N-acetylglucosamine. Diatoms have a unique cell wall composed of biogenic silica.

A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods (kraft and sulfite processes). The finished product may be either bleached or non-bleached, depending on the customer requirements.

Wood and other plant materials used to make pulp contain three main components (apart from water): cellulose fibres (desired for papermaking), lignin (a three-dimensional polymer that binds the cellulose fibres together) and hemicelluloses, (shorter branched carbohydrate polymers). The aim of pulping is to break down the bulk structure of the fiber source, be it chips, stems or other plant parts, into the constituent fibers.